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close this book Practical poultry raising
close this folder 3. Getting to know the chicken
View the document Characteristics of chickens
View the document Anatomy of chickens
View the document Handling live chickens
View the document Catching chickens

Anatomy of chickens

To be able to work with chickens, you first must know the various parts of a chicken and their functions, and how to tell male and female chickens apart. The major external parts of a chicken include these:

• Beak - The chicken's beak serves three functions. First, it is the chicken's mouth. Second, it is used for fighting and protection. And third, it functions as the teeth of the chicken, enabling the bird to break grass, bananas and other foods into pieces small enough to swallow.

• Comb and wattles - It is believed that the comb and wattles of chickens serve to cool their blood.

Figure 6

• Ear lobes - The ear lobes of chickens serve hearing and other ear functions.

• Eyes - The eyeball of a chicken is stationary; thus, a chicken must move its head to vary the range of vision

• Feathers - Feathers provide insulation and bufter extremes of heat and cold.

• Wings - Chickens cannot fly very well. They can flap their wings sufficiently to raise themselves about three meters (m) off the ground

• Tail and tail feathers - The tail is used for balance while walking and, in flying, as a rudder for up - and - down and side - to - side motion.

• Feet and claws - In addition to walking, feet and claws are used in fighting (for protection) and in finding food.

There are several differences between male and female chickens that should help in identification.

These are:

• Size - The male will grow taller and usually weighs between 0.5 and 1 kg (1 to 2 pounds) more than females of the same age upon reaching maturity. A male of one breed may weigh less than the female of another breed. This greater size is not apparent until the chicken attains four weeks of age. At one day old there is no difference at all between male and female chicks.

• Comb and spurs - The comb of the male will become much larger than the comb of a female. On the female, spurs hardly develop at all when compared to the male.

• Vocal expressions - Everyone knows that a rooster crows while a hen doesn't. What is not generally known is that roosters crow intermittently all day long, not just in the morning.

• Feathers - Adult males have distinguishably different feathers from those of adult females. The most distinguishable are the tail feathers which are long and stringy on the male.

Usually male chickens of improved layer breeds are destroyed within a day or two after they are taken from the incubator because it is uneconomical to raise them for meat. In the case of improved meat breeds, both female and male are of economic value and are raised.

Internal Anatomy of Chickens

Although it is not expected that you will become an expert, it will be useful for you to understand the anatomy and functions of different organs of chickens. Chickens do not have stomachs like other animals, but have a different means of food storage and digestion. First the food enters the beak (mouth) and goes halfway down the esophagus (throat) to a storage area called a crop where it is moistened and thus softened. Food then continues down the remainder of the esophagus and enters what is called the proventriculous, or true stomach. The proventriculous secretes digestive juices (enzymes and acids), and is directly attached to the gizzard which grinds food up into smaller pieces. Food leaving the gizzard enters the small intestine where nutrients are picked up by blood vessels and circulated throughout the chicken's body. Food particles then move into the large intestine, which has two "blind" or dead end attachments called ceca. (The functions of the ceca are not understood fully.) After digestion in both intestines, the waste materials including both urine and stool are excreted through one opening called the vent. The excreted material is called feces.

The heart and lungs of a chicken function in the same way as these of most other animals. Air enters through the nostrils then goes down a tube called the trachea, located right beside the esophagus. Both tubes are located on the under side of the neck when the chicken is standing. The entrance point to this air tube is located at the back of the mouth and is called the larynx. The trachea looks like a thin plastic tube with rings around it. This ends at a Y - shaped junction and two bronchial tubes lead off to the right and left lungs. The trachea and bronchial tubes look like semi - transparent plastic tubes. The lungs are segmented and located between the rib bones leading from either side of the back bones of the chicken. Going further back towards the tail, you find the reproductive system, then, closest to the tail, there are pockets in a larger bone which contain the kidneys. If normal, the kidneys are brownish red in color.

If you open the chicken lying on its back, the first thing you will see is the liver which is divided into two parts, just forward of the soft skin above the vent. There is often yellow or white fat between the skin and the liver. The normal liver is the same or slightly lighter color than the typical animal liver found in a marketplace. Under and forward of the liver you will find a small sac of green fluid. This is the gall bladder. After you pick up the liver and the intestines, you will find a small ball - shaped organ, the spleen, above the kidneys. The spleen is lighter in color than the kidneys.

In the female adult chicken, if it is laying eggs, you will find to the rear of the lungs and along the back the ovary, which consists of a mass of egg yolks ranging in size from microscopic to almost an inch in size. The smaller ones will be opaque. Egg yolks enter a tube through what is called the funnel. The funnel leads to the oviduct through which the yolk passes and in which the egg white, then the shell, is formed, a process which takes about 24 hours. Upon mating with a rooster, sperm passes through the oviduct system in the opposite direction. Fertilization takes place at the ovary end. Sperm may stay viable for up to 4 weeks and are stored in the oviduct. The best way to learn about the chicken is to go to the market place and buy a chicken. If you are not willing to kill a chicken yourself, have it killed. Later on, you'll get used to killing chickens if you work with them very much. If there are no chickens in the market, buy one from a farmer. Watch the way he kills it. You may want to use the same method used by the farmer. In any case, take it home and try to find all the parts of the chicken described above. Do this several times, until you have learned the parts. If possible, go to a veterinarian for a test, using a male and a female chicken. (Don't go to the veterinarian until you have tried on your own several times. If you go too early, all you will do is memorize and forget what is shown to you.)